In recent years, in the field of producing semiconductors, in order to make it possible to transfer patterns having a size further microsized, EUV exposure technology is expected to be promising in place of ArF exposure technology using ArF excimer laser light. In the EUV exposure technology, as the exposure light, EUV (Extreme Ultra-Violet) light having a shorter wavelength than ArF excimer laser light, is used. Here, EUV light includes soft X-ray and vacuum ultraviolet light, and it is specifically light having a wavelength of from about 0.2 nm to 100 nm. At present, as the exposure light, EUV light having a wavelength of about 13.5 nm is mainly investigated.
In the EUV exposure technology, a reflective mask is used. This mask is produced by constructing a reflective mask blank by forming various layers including a reflective layer and an absorber layer, on a substrate, and patterning the absorber layer of the reflective mask blank in a prescribed pattern.
In the EUV exposure technology, by radiating EUV light, via such a mask, to a substrate such as a wafer to be processed, it is possible to transfer the pattern of the absorber layer to the surface of the substrate to be processed (usually the surface of a resist) (hereinafter, this process will be referred to also as a “transfer process”). Then, the resist is subjected to development treatment, whereby it is possible to obtain a processed substrate having the resist with the desired pattern formed (Non-patent Document 1).